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Abstract The application of an innovative translucent superinsulated latent heat storage wall, combining transparent insulation material and phase change materials (TIM-PCM wall), on the envelope of a typical office under different climates is evaluated. Energy and economic analysis related to this application are presented. The simulation process is carried out using an experimentally validated numerical model. The results show that the incorporation of the TIM-PCM wall, on the south orientation, is more efficient than the use of a double-glazed in all considered climates. The optimum TIM-PCM wall area is evaluated economically through life-cycle cost and payback period analysis. The purpose is to ensure effective performance of the wall in each climate and at the same time to ensure economic viability. The results show that, in polar and subarctic climates, the application of the TIM-PCM wall has a high economic value and the investment appears to be attractive, the payback period being 10.5 years and 7.8 years respectively. In Dras (continental climate), the use of the wall is found economically unfeasible due to low energy prices and high discount rates. At current prices, the TIM-PCM wall investment in Sacramento (Mediterranean climate) and Toronto (Humid continental) does not offer economic benefits. Highlights • Application of the TIM-PCM wall under different climates. • Energy and economic analysis related to the application of the TIM-PCM wall. • Evaluation of the optimum TIM-PCM wall area in each climatic condition. • Economic viability depends on climatic conditions, energy price and investment cost. [ABSTRACT FROM AUTHOR]

This study experimentally investigates the supercooling and natural convection behavior in three PCM, namely pure octadecane (organic), a eutectic PCM, and sodium acetate trihydrate (inorganic). The aim is to explore the effect of different factors on the degree of supercooling and on the natural convection, and to provide data for numerical simulation models. Results show that the type of PCM, the temperature of the cooling fluid, and mechanical shocks have a direct effect on the degree of supercooling. The supercooled PCM shows a high sensitivity to any changes in the applied conditions. The thermal insulation of the unheated PCM boundaries has a major effect on the solidification and melting dynamics and topology, particularly regarding the solid-liquid interface. The cross-sectional temperature profiles, the inclination of the solid-liquid interface, and the melting rate show that regardless of the PCM, natural convection plays a significant role during heating but not during cooling. [ABSTRACT FROM AUTHOR]

• The interconnections distribution in fibers determines the heat transfer model. • The development of a thermal conductivity equation considers the radiative heat transfer. • The bale's thermal conductivity varies according to the fiber orientation. • Thermal conductivity depends on the chemical composition of the straw. Straw fibers are natural fibers that have a strong insulating property and a minimal environmental effect, making them suitable construction materials. In the construction sector, to predict the building energy consumption, the thermal conductivity of the materials composing the envelopes must be precisely known, which is not the case for the straw material. The properties of a straw bale are variable and mainly depend on its density, fibers orientation, chemical composition, temperature and relative humidity. Consequently, this study consists of determining a mathematical equation to predict the effective thermal conductivity of straw bales that can be applied to all straw types, in different circumstances. For this purpose, the size, distribution, and morphology of straw fibers are first determined from microscopic images. Second, a mathematical model for estimating the thermal conductivity is suggested using the heat transfer models of porous and fibrous materials. The numerical model is validated by an experimental study that measures the thermal conductivity of straw bales by altering their density between 80 and 120 kg/m3, their relative humidity between 15 % and 95 %, and their temperature between 15 ˚C and 55 ˚C. The experimental results show that the thermal conductivity increases from a minimum of 0.047 W/(m∙K) to a maximum of 0.09 W/(m∙K) when increasing the three altered factors. For a straw fiber having 40% cellulose content, the thermal conductivity increased from a minimum of 0.05 W/(m∙K) to a maximum of 0.0832 W/(m∙K). This behavior is found the same for the numerical findings. The comparison of numerical and experimental values shows a good agreement, with a root mean square error of 0.005 W/(m∙K) and a scatter index of 5.5 %. [ABSTRACT FROM AUTHOR]

This paper investigates the thermal performance of a translucent solar wall providing, concurrently, storage and restitution of heat, super thermal-acoustic insulation and daylighting to the interior environment. The wall is composed of glazing, silica aerogel used as a transparent insulation material (TIM) and glass bricks filled with fatty acid, an eutectic phase change material (PCM). To assess the TIM–PCM wall thermal behavior, experimentations were conducted in-situ in a full-sized test cell located in Sophia Antipolis, southern France. Experimental data shows that the tested wall is more effective in winter and might cause overheating during the summer mainly due to solar gains and un-cycling behavior of PCM which remains in liquid state. To enhance the energy performance of the wall in summertime, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers is developed. Then, the model of the wall is linked to TRNSYS software to assess the thermal performance of the whole building. The numerical model is validated experimentally and a good agreement is shown comparing the simulated values with the measured data for seven consecutive days in summer and winter. The importance of considering the natural convection effect in the liquid PCM is also demonstrated. Moreover, it was shown that shading devices can effectively reduce overheating while natural night ventilation decreases the indoor temperature without affecting the PCM performance since the outdoor temperature is always higher than the phase change temperature. The use of a glass with selective solar reflection properties depending on the season instead of the ordinary glazing is shown also to be very effective way to overcome the overheating problem. Finally, the TIM-PCM wall is tested under different climate conditions and passive solutions are given to ensure thermal comfort in summer season. [ABSTRACT FROM AUTHOR]

This paper details a numerical study of solid-liquid phase change heat transfer in a rectangular enclosure with the aim of optimizing the number, dimension, and positioning of fins in the enclosure. The enclosure is exposed on one side to a constant heat flux of 1000 W/m 2 for 3 h and both the total fin mass and the PCM mass are kept constant in all simulated cases. The heat diffusion equation in the PCM uses the equivalent heat capacity method while natural convection driven PCM motion in the enclosure is modeled through the buoyancy force, using a modified viscosity and an additional volume force term in the Navier-Stokes momentum conservation equation. Three efficiency assessment parameters are used: (i) the height-averaged temperature of the front hot plate which should remain as low as possible for the longer possible time, (ii) the energy stored inside the PCM as a function of time, and (iii) the heat transfer rate and heat flux between the front plate and the PCM. For each simulated case, complementary data such as the standard deviation of temperature along the heated plate and the ratio of sensible heat to latent accumulation are also calculated. Results show that increasing the number of fins diminishes both the stabilization temperature and the stabilization time of the front plate during phase change, and accelerates the sensible and latent storage of energy in the PCM. Using thinner but longer fins provides the same impact except that the stabilization time also increases as the fin length is increased. Besides, at constant fin mass, varying fin spacing have marginal impact on the latent heat storage performance and on the hot plate temperature stabilization. The study also shows that the surface area plays the largest role in the increase of the heat transfer rate between the front plate and the PCM, while configurations which can promote stronger natural convection lead to higher heat flux. Finally, it was observed that systems allowing easier heat transfer to the back plate during melting provide a higher ratio of sensible heat to latent accumulation, while the standard deviation of the front plate temperature decreases as the number of fins or the spacing between fins increases. [ABSTRACT FROM AUTHOR]

Experimental measurement still plays an important role in indoor airflow study. To obtain three-dimensional and high-quality experimental data in building's indoor airflow study, Particle Tracking Velocimetry (PTV) and Particle Image Velocimetry (PIV) have been increasingly used. The accuracy and precision of measurement technologies is always a crucial issue. This paper first numerically compares the measuring performance of 3D PTV and typical 2D PIV algorithms on three laminar macro scale flows of known displacement, as a function of the particle tracking density defined as the ratio of mean particle spacing to mean particle displacement. Then, 3D PTV and 2D PIV results are compared using an experimental low-turbulence indoor airflow generated by a low-speed tailpipe. Results suggest that when the tracking density is smaller than two, 3D PTV generally cannot yield reliable measurement results. As the tracking density increases, 3D PTV has a better ability to measure larger displacement than PIV. [ABSTRACT FROM AUTHOR]

In France, renovation of existing buildings has a high priority. The thickness of insulation layers becomes a major issue of concern especially in cities. In this study, we present a recently developed insulating rendering based on silica aerogels that can be applied to new buildings and to retrofit existing ones. A full scale experimental house is built near Chambery in France, with the rendering applied on its external facades. The results of a numerical model developed in EnergyPlus are compared to the on-site measurements. After validating the numerical model, the thickness of the rendering is optimized based on a cost analysis for different climates for the case of retrofitting an old building. Then, a sensitivity analysis is carried out to determine the thickness dependency on annual heating load, present worth factor, rendering’s cost, and heating set-point. Results show that the optimum rendering thickness is in the range of 1.7–4.4 cm and the payback period in the range of 1.4–2.7 years depending on the climate. The optimum thickness increases with the increasing heating set-point and increasing present worth factor; however, it decreases with the increasing rendering cost. [ABSTRACT FROM AUTHOR]

This paper presents the first passive solar wall providing simultaneously super insulation, heat storage and daylighting to the inner space. The wall’s external layer is composed of a silica aerogels bed for high insulation and solar radiation transmission. The second layer, internal, is composed of glass bricks filled with a eutectic phase change material (PCM) for heat storage and restitution. The whole wall is translucent. The experimentations carried out to characterize thermal and optical properties of the materials used are described. Then results are given for a full scale comparative experimentation on a twin zones building located in the south of France for the solar wall and a standard opaque high thermal capacity wall. Results show the heat losses through the wall are very low while the heat and light gains are high: The U value of the solar wall is 0.59 W m −1 K −1 and 0.72 W m −1 K −1 respectively when the PCM is in liquid and solid state. With the test building in free floating condition, the temperature difference between the outdoor and indoor air provided by the wall is about 9 °C in winter. The wall can provide up to 500 lux to the inner environment, which is sufficient for conference rooms. The tested wall has proven more effective in winter and shoulder season, particularly for cold sunny climates, but may cause overheating in summer. [ABSTRACT FROM AUTHOR]

Airflow field measurement plays a significant role in creating a thermally comfortable indoor environment, by providing adequate quantitative information of indoor air distribution and local air velocity. In recent years, the Particle Tracking Velocimetry (PTV) technique has gradually become a promising and powerful tool for indoor airflow field measurement. This paper firstly gives an overview of the equipments and methods involved in typical PTV applications to indoor environments, and then introduces related applications of PTV for measuring indoor airflow fields. The Particle Streak Velocimetry (PSV) technique for indoor airflow measurement is also introduced. This paper shows how the quantitative and detailed turbulent flow information obtained by PTV measurement is critical for analyzing turbulent properties and developing numerical simulations. The limitations and future developments of PTV and PSV techniques are also discussed. [ABSTRACT FROM AUTHOR]

This study aims at examining the energy behaviour of the buildings' multi-layer exterior wall structures. Most of the studies dealing with this issue have considered a continuous operation of the cooling/heating systems. Our objective here is to find the best wall structure and the number and position of insulation layers within exterior walls for continuous heating, intermittent heating, and no heating operation modes for some commonly used construction materials. Furthermore, among the different materials used, a recently patented insulating coating based on the (super)-insulating materials “Silica Aerogels” is being assessed. Results from a one-dimensional heat transfer numerical model in a multi-layer wall structure are compared to on-site measurements of an experimental set-up, having the new aerogel-based coating, under real weather conditions. The numerical model is then used to carry out all the simulations. Several assessment parameters are used: time lag, decrement factor, energy consumption, and thermal comfort index. Results show that for continuous and no heating cases, the best wall from maximum time lag and minimum decrement factor perspective is dividing the insulation layer into two and placing one at the middle of the wall and one at the exterior surface. For intermittently heated spaces, placing the insulation material as one layer at the interior wall surface is the most efficient from an energy consumption perspective. Also, when using the thermal comfort index for the no heating operation mode, the best performance is achieved when placing the insulation at the interior wall surface. For most of the cases studied, the aerogel-based insulating coating shows better performance than other insulating materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] Co-simulation is used; coupling a 2D heat transfer code developed in MATLAB with EnergyPlus. [•] Windows offset thermal bridges energy load constitutes around 2-8% of the total house load. [•] Applying the coating reduces the windows offset thermal bridge load by about 24% to 50%. [ABSTRACT FROM AUTHOR]

Highlights: [•] A volume force was added to the buoyancy term in the Navier–Stokes’ momentum conservation equation. [•] Using PCM kept panel temperature under 40°C for 80min under radiation of 1000W/m2. [•] Adding cooling fins does not always help maintaining the panels’ temperature low. [ABSTRACT FROM AUTHOR]

In this paper, melting of a phase change material (PCM) inside a rectangular enclosure, possibly finned and inclined, is studied numerically. The application of this work is related to the temperature control of a finned PV panel filled with PCM and installed at different tilt angles. The studied system is modeled as a 2D rectangular enclosure filled with PCM (RT25) and packed between two aluminum plates, where the front side is exposed to a constant heat flux of 1000 W/m2 for 2 h. Four geometries were considered including a non-finned PCM enclosure, a PCM enclosure with one centered full-width fin, one half-width fin attached to the front plate, and one half-width fin attached to the back plate. Results have shown that the most efficient thermal management of the PV-PCM panel is obtained when the PCM enclosure is equipped with a full-width fin simultaneously attached to the front and back plates. With such a PV panel design, the PCM melting is dominated by natural convection heat transfer from both sides of the PCM enclosure at an early stage, with added heat losses from the back plate to the external environment. Accordingly, low values of the front and back plates temperatures can be maintained during a stabilization time of 80 min as long as the tilt angle is varied from 0° to 75° from the vertical. The efficient temperature control resulting from the full-width fin geometry is mainly related to the high overall heat transfer coefficient obtained during the whole melting process. [ABSTRACT FROM AUTHOR]

The shift towards using materials derived from plants is considered an innovative approach to creating eco-friendly buildings and decreasing the energy expenses associated with the building sector. This study aims to provide a comprehensive analysis of these materials' hygrothermal properties to support their successful integration in both new construction and building renovation projects. It reviews the current state of research on the thermal and hydric properties of plant materials on various scales: raw aggregate/fiber, plant-based composite, wall, and building scale. The first part focuses on the physical, chemical, and hygrothermal characterizations of raw plant aggregates and fibers. The second part covers the main hygrothermal properties of plant-based composites (insulation boards and concretes) and compares their performance with conventional materials. The study then shifts its focus to the hygrothermal performance of walls integrated with plant-based materials in response to external climate conditions. Finally, a review of full-size buildings is conducted to investigate the impact of these materials on hygrothermal behavior at the building scale and to highlight their influence on the reduction of energy consumption. A lack of studies on plant-based materials was observed. There remain numerous areas that require further investigation at each scale. Consequently, the study includes discussion sections that provide guidance for future research to fill the gaps and advance the development of this type of material. • Up-to-date literature on plant-based building materials at various scales is reviewed. • The physical, chemical, and hygrothermal properties of raw plant aggregates and fibers are discussed. • The hygrothermal properties of plant-based composites, insulation boards, and concretes are discussed. • The application of plant materials at the wall scale is reviewed. • The hygrothermal comfort and energy performance of plant-based composites at the building scale are highlighted. • Future studies are proposed to fully explore the potential of plants as sustainable building materials. [ABSTRACT FROM AUTHOR]

Net-zero energy buildings (NZEBs) have been considered as an efficient solution to limit the growing energy consumption and pollution emissions from buildings. The configurations and the capacities of the implemented renewable energy systems in NZEBs should be wisely selected to ensure the intended performance objective. This study aims to optimize, investigate and compare six renewable energy solution sets for designing NZEBs in three different climates: Indore (cooling dominant), Tromso (heating dominant), and Beijing (mixed climate). The optimization is carried out using a multi-criteria decision-making methodology. The implemented methodology is composed of two phases. In the first phase, the optimal sizes of solution sets in each climate are derived and analyzed. The effectiveness of optimal solution sets is evaluated with respect to economy, environment, energy and grid stress. In the second phase, recommendations for each region are offered according to the overall performance evaluation results. The evaluation criteria include life cycle cost, payback period, levelized cost of energy, CO 2 eq emissions, grid interaction index, load matching index, and total energy consumption. The analyses show that, in Indore (hot climate), it is recommended to utilize the solution set composed of air source heat pump for cooling and flat plate solar collectors for domestic hot water (DHW) production. In Tromso (cold climate), the use of a biodiesel generator is promising to produce both electricity and hot steam for heating as well as DHW use. In Beijing (mixed climate), it is recommended to utilize electric chillers for cooling and natural gas condensing boiler for heating and DHW usage. • Renewable energy solution sets for net zero energy building are optimized. • Hot, cold and mixed climates are investigated. • Building performance is analyzed in terms of energy, cost, and CO 2eq emissions. • Load matching and grid stress analysis is conducted. • Suitable design options for each climate are offered. [ABSTRACT FROM AUTHOR]

Abstract Worldwide, the residential buildings are consuming a considerable amount of energy. The high potential of buildings towards energy efficiency has drawn special attention to the passive design parameters. A comprehensive study on optimal passive design for residential buildings is presented in this paper. Twenty-five different climates are simulated with the aim to produce best practices to reduce building energy demands (for cooling and heating) in addition to the life-cycle cost (LCC). The occupants' adaptive thermal comfort is also improved by implementing the appropriate passive cooling strategies such as blinds and natural ventilation. In this respect, the implemented methodology is composed of four phases: building energy simulation, optimization, Multi-criteria Decision Making (MCDM), sensitivity study, and finally an adaptive comfort analysis. An optimal passive solution of the studied building indicates the potential to save up to 54%, 87% and 52% of the cooling demands (Qcool), heating demands (Qheat) and LCC respectively with respect to the initial configuration. The obtained optimal passive parameters are validated with the National Renewable Energy Laboratory NREL benchmark for low energy building's envelope. Additionally, the integrated passive cooling strategies have demonstrated its competency since it leads to a significant overheating decrease. Highlights • Residential building's passive design parameters are optimized. • Effect of different climates of Köppen Geiger classification is studied. • Thermal comfort and energy performance of the case-studies are significantly enhanced. • Passive cooling strategies lead to adequate thermal comfort and fewer cooling systems. [ABSTRACT FROM AUTHOR]

In the cold sunny winter days, when the south wall is well insulated, a significant amount of solar energy falling on this facade is not transferred to the inside. In this study, a novel closed wall-loop system is proposed to capture this wasted energy available during non-cloudy winter days and transfer it to the cooler north facade through water pipes embedded in an exterior aerogel-based insulating coating. The coating's projection technique through spraying or plastering allows the easy implementation of this system. We present the proposed system with all the mathematical equations and numerical model. This model is then validated against experimental data found in the literature. To test its performance on a full-scale house, this MATLAB numerical model is coupled to the whole building energy simulation program EnergyPlus through co-simulation. Results show that the reductions in the annual heating load for the house adopting this system relative to the one without it are between 28 and 43% for new houses and 15–20% for old houses for Mediterranean climate. For other climates, the reductions vary between 6% and 26%. The heat losses through the north facade are reduced by about 60–88% in the Mediterranean climate and about 20–50% in the other climates. [ABSTRACT FROM AUTHOR]

The thermal conductivity of commonly used phase change materials (PCM) for thermal energy storage (TES), such as, fatty acids, paraffin etc., is relatively poor, which is one of the main drawbacks for limiting their utility. In the recent past, few attempts have been made to enhance the thermal conductivity of PCM by mixing different additives in the appropriate amount. Graphene nanoparticles, having higher thermal conductivity may be a potential candidate for the same, when mixed appropriately with different PCM. In present study authors have carried out the numerical investigation for the melting of graphene nano-particles dispersed PCM filled in an aluminum square cavity heated from one side. In this work, the graphene nanoparticles are mixed in three different volumetric ratios (1%, 3%, and 5%), with three different commonly used categories of organic, inorganic and paraffin PCM (namely, Capric Acid, CaCl 2 ·6H 2 O, and n -octadecane) to see the effect on melting of composite PCM developed. The resulting transient isotherms, velocity fields, and melting front and melt fractions thus have been deliberated in detail. These results clearly indicate that the addition of graphene nanoparticles increases melting rate but can also hamper the convection heat transfer within large cavities. The study also shows that such enhanced PCM can be effectively used for different TES applications in different fields. The prediction of temperature variation and rate of melting or solidification may be found useful especially for designing such TES devices. [ABSTRACT FROM AUTHOR]

Solar Photovoltaic (PV) cells can absorb up to 80% of the incident solar radiation obtained from the solar band, however, only a small amount of this absorbed incident energy is transformed into electricity depending on the conversion efficiency of the PV cells and part of remainder energy increases the temperature of PV cell. High solar radiation and ambient temperature lead to an elevated photovoltaic cell operating temperature, which affects its lifespan and power output adversely. Number of techniques have been attempted to maintain the temperature of photovoltaic cells close to their nominal operating value. In the present review various cooling techniques such as natural and forced air cooling, hydraulic cooling, heat pipe cooling, cooling with phase change materials and thermoelectric cooling of PV panels are discussed at length. It is important to note that, though cooling techniques are highly needed to regulate the PV module temperature, especially for mega installations, these should be economically viable too. [ABSTRACT FROM AUTHOR]

The higher operating temperature of photovoltaic panels (above the standard operating temperature, usually 25 °C) adversely affects the panel’s efficiency. PV panel coupled with phase change materials (PCM) could be a feasible solution due to the higher energy storage density of such materials. However, heat transfer studies of PCM combined with PV panel are quite intricate due to variable ambient conditions and changing thermo-physical property of the material with phase change. In the present study, detailed heat transfer study of the PV panel coupled with PCM has been performed. The computational fluid dynamic study of the PV module coupled with PCM is carried out in which essential heat transfer mechanisms between PV module to PCM and environment have been accounted for. Additionally, its effect on power output has been investigated to see the variation of PV module operating temperature. This study clearly suggests that for realistic simulation of heat and mass transfer studies of PV panel attached with PCM, it is very important to consider following effects into account: convection effect within melted PCM, the velocity of wind, and angle of inclination of PV panel. The results from the study demonstrate the ability and importance of such model to reasonably simulate the thermal characteristics of PV panels coupled with PCM. The maximum panel operating temperature with conduction and convection effect is found to be 54.90 °C and 58.5 °C when convection mode in melted PCM (only conduction mode) is not considered. It has also been shown that the higher wind velocity and tilt angle leads to lower operating temperature of PV panels. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) panels, depending on the PV cell technology used, convert only a small amount of incident energy into electricity (about 5–25% for commercial systems), and the rest is converted into heat. The produced heat is partly transferred back to the environment while the remaining part causes the enhancement of the PV panel temperature itself. This increase in the PV panel temperature further affects power production adversely, if the PV panel temperature rises above the standard operating temperature (usually 25 °C). The present study deals with the thermal analysis of PV panel involving (i) numerical study based on finite element heat transfer, (ii) the outdoor experimental validation of the thermal model developed. The thermal model is based on the energy balance of the PV module in which all essential heat transfer mechanisms between the module to the environment and related power output are modeled to observe the net change in PV module temperature. The results clearly demonstrate the need and ability of the model to realistically simulate the thermal behavior of PV panels. Additionally, using the same model, numerical simulations have been also carried out for two different cities, namely Allahabad and Jodhpur, for Indian climate, to predict the hourly average module temperature of PV panels for different months. The results show that normal module temperature is raised much above the standard test conditions for the months of April, May and June. [ABSTRACT FROM AUTHOR]

• The temperature and relative humidity variations obtained by WUFI are in good agreement with the literature experimental findings. • The excessive moisture content in straw leads to bio-deterioration, mold, and decay damage in the whole structure. • The hygrothermal issues in a straw wall depend on the interior and exterior covering layers. • Hygrothermal issues can be solved by adding the straw thickness, adding a vapor retarder layer, adding an unventilated air layer, and controlling the indoor conditions. Straw is becoming a promising alternative insulation material to improve the building energy performance because of its low cost, large availability as cereal waste, its good hygrothermal properties, and its low embodied energy. The goal of this paper is to assess the hygrothermal performance of multi-layered straw walls with different boundary conditions. The study consists of evaluating five different straw-based wall assemblies, under a continental (Arkhangelsk, Russia), a tropical climate (Brasilia, Brazil), a temperate Mediterranean climate (Nice, France), and a cold desert climate Xinjiang (China). Numerical models of the heat and moisture transfer through the walls using WUFI software are developed, calibrated, and validated through experimental results from the literature. The chosen evaluation criteria are the total water content, the drying rate, the condensation risk, the mold growth, the moisture quantity, the time lag, and the decrement factor. Results show that straw walls with cement and/or wood covering can be used in tropical and temperate climates, coated straw walls with additional air layers in dry climates, while insulated straw walls are best fitted in continental climates. In the latter, the dryness rate varies between 7 and 40% with a low condensation risk of value in the range of 0–12%. It can be concluded that the straw wall's performance strongly depends on the interior and exterior added thermal insulation layers since they affect the ability of the material to dry out. [ABSTRACT FROM AUTHOR]

• Microscopic structure characterization of straw fibers. • Thermal and mechanical properties of straw bales. • Fire and sound resistance of a straw bale walls. • Life cycle assessment of a straw construction. • Energy and economic performance of straw bale buildings. Bio-based materials such as straw are becoming a promising alternative to improve the building energy performance and to reduce its carbon footprint. When compared to common building construction materials, bio-based materials control the temperature and the relative humidity variation to ameliorate the indoor comfort with a low embodied energy and CO 2 emission. This paper presents a comprehensive review of the thermal and mechanical properties of straw-based materials and buildings. The objective is to synthesis the work that has been carried out by the research community and to compare the results. The paper first introduces straw bale as a construction material from a historical viewpoint and in the context of the current building sector. The second part focuses on the available chemical and microstructural data of the straw fiber. The third part refers to the thermophysical and mechanical properties of the bales. The fourth part reviews the numerical and experimental studies done at the wall scale. The fifth part describes straw bale construction methods considering the regulation, structure requirements, and life cycle assessment data. Last, a critical analysis of the currently available data on straw as a building material is carried out and pending research issues are discussed. It was found that, despite abundant literature on structural and thermal properties of straw bale constructions, there is still a lack of some information. At a fiber scale, more research should be done to compare straw fibers to other natural and synthetic fibers. At a bale scale, further pH-related research is needed because it affects the material's interior conditions and durability. In addition, a thermal conductivity model for straw should be developed. On a bigger scale, the hygrothermal characteristics of various types of walls must be measured and computed experimentally and theoretically under various exterior and internal situations. More research is needed to improve the sound resistance of the straw wall by adding new layers capable of absorbing acoustic waves. Studies on the energy behavior, cost analysis, and how interior air moisture is self-regulated in straw buildings are needed at the building size. Therefore, a lack of consistent data among the different studies was noted depending on the straw characteristics. [ABSTRACT FROM AUTHOR]